Susan Sontag, one of America's most influential intellectuals, internationally renowned for the passionate engagement and breadth of her critical intelligence and her ardent activism in the cause of human rights, died today of leukemia. She was 71.

The author of 17 books translated into 32 languages, she vaulted to public attention and critical acclaim with the 1964 publication of "Notes on Camp," written for Partisan Review and included in "Against Interpretation," her first collection of essays, published two years later.

Sontag died at Memorial Sloan Kettering Cancer Center in New York City.

Sontag wrote about subjects as diverse as pornography and photography, the aesthetics of silence and the aesthetics of fascism, Bunraku puppet theater and the choreography of Balanchine, as well as portraits of such writers and intellectuals as Antonin Artaud, Walter Benjamin, Roland Barthes and Elias Canetti.

Sontag was a fervent believer in the capacity of art to delight, to inform, to transform.

"We live in a culture," she said, "in which intelligence is denied relevance altogether, in a search for radical innocence, or is defended as an instrument of authority and repression. In my view, the only intelligence worth defending is critical, dialectical, skeptical, desimplifying."

In a Rolling Stone article in 1979, Jonathan Cott called Sontag a writer who was "continually examining and testing out her notion that supposed oppositions like thinking and feeling, consciousness and sensuousness, morality and aesthetics can in fact simply be looked at as aspects of each other — much like the pile on the velvet that, upon reversing one's touch, provides two textures and two ways of feeling, two shades and two ways of perceiving."

She wrote four novels, "The Benefactor," "Death Kit," "The Volcano Lover," and "In America," which won the 2000 National Book Award for fiction.

Sontag was born Jan. 16, 1933, in New York City and raised in Tucson and Los Angeles, the daughter of an alcoholic schoolteacher mother and a fur trader father who died in China of tuberculosis during the Japanese invasion when Sontag was 5. She was a graduate of North Hollywood High School and attended UC Berkeley and the University of Chicago — which she entered when she was 16 — and Harvard and Oxford.

In 1950, while at the University of Chicago, she met and 10 days later married Philip Rieff, a 28-year-old instructor in social theory. Two years later, at age 19, she had a son David, now a prominent writer. She was divorced in 1959 and never remarried.

Sontag was reading by 3. In her teens, her passions were Gerard Manley Hopkins and Djuna Barnes. The first book that thrilled her was "Madame Curie," which she read when she was 6. She was stirred by the travel books of Richard Halliburton and the Classic Comics rendition of Shakespeare's "Hamlet." The first novel that affected her was Victor Hugo's "Les Miserables."

"I sobbed and wailed and thought [books] were the greatest things," she recalled. "I discovered a lot of writers in the Modern Library editions, which were sold in a Hallmark card store, and I used up my allowance and would buy them all."

She remembered as a girl of 8 or 9 lying in bed looking at her bookcase against the wall. "It was like looking at my 50 friends. A book was like stepping through a mirror. I could go somewhere else. Each one was a door to a whole kingdom."

Edgar Allan Poe's stories enthralled her with their "mixture of speculativeness, fantasy and gloominess." Upon reading Jack London's "Martin Eden," she determined she would become a writer. "I got through my childhood," she told the Paris Review, "in a delirium of literary exaltations."

At 14, Sontag read Thomas Mann's masterpiece, "The Magic Mountain." "I read it through almost at a run. After finishing the last page, I was so reluctant to be separated from the book that I started back at the beginning and, to hold myself to the pace the book merited, reread it aloud, a chapter each night."

Sontag began to frequent the Pickwick bookstore on Hollywood Boulevard, where she went "every few days after school to read on my feet through some more of world literature — buying when I could, stealing when I dared."

She also became a "militant browser" of the international periodical and newspaper stand near the "enchanted crossroads" of Hollywood Boulevard and Highland Avenue, where she discovered the world of literary magazines. She was fond of recounting how, at 15, she had bought a copy of Partisan Review and found it impenetrable. Nevertheless, "I had the sense that within its pages momentous issues were at stake. I wanted desperately to crack the code."

At 26, she moved to New York City where, for a time, she taught the philosophy of religion at Columbia University. At a cocktail party, she encountered William Phillips, one of Partisan Review's legendary founding editors and asked him how one might write for the journal. He replied, "All you have to do is ask." "I'm asking," she said.

"I love to read the way people love to watch television," she told Rolling Stone. For her, culture was a vast smorgasbord, a movable feast. The point, she often said, quoting Goethe, was "to know everything."

"So when I go to a Patti Smith concert, I enjoy, participate, appreciate and am tuned in better because I've read Nietzsche. The main reason I read is that I enjoy it. There's no incompatibility between observing the world and being tuned into an electronic, multimedia, multi-tracked, McLuhanite world and enjoying what can be enjoyed about rock 'n' roll."

Sontag devoted herself to demolishing "the distinction between thought and feeling, which is really the basis of all anti-intellectual views: the heart and the head, thinking and feeling, fantasy and judgment. Thinking is a form of feeling; feeling is a form of thinking."

Her quest was admired by such writers as Elizabeth Hardwick, a founder of the New York Review of Books, whose editors quickly embraced Sontag. In her introduction to "A Susan Sontag Reader," Hardwick called her "an extraordinarily beautiful, expansive, and unique talent."

Each of Sontag's essays, Hardwick wrote, "has a profound authority, a rather anxious and tender authority — the reward of passion. The tone of her writing is speculative, studious and yet undogmatic; even in the end it is still inquiring."

Others were less impressed. John Simon accused Sontag of "a tendency to sprinkle complication into her writing" and of tossing off "high-sounding paradoxes without thinking through what, if anything, they mean." Greil Marcus called her "a cold writer" whose style was "an uneasy combination of academic and hip pedantic, effete, unfriendly." Walter Kendrick found her fiction "dull and derivative."

In 1976, at 43, Sontag discovered she had advanced cancer in her breast, lymphatic system and leg. She was told she had a one-in-four chance to live five years. After undergoing a radical mastectomy and chemotherapy, she was pronounced free of the disease. "My first reaction was terror and grief. But it's not altogether a bad experience to know you're going to die. The first thing is not to feel sorry for yourself."

She learned as much as possible about the disease and later wrote "Illness as Metaphor," an influential essay condemning the abuse of tuberculosis and cancer as metaphors that transfer responsibility for sickness to the victims, who are made to believe they have brought suffering on themselves. Illness, she insisted, is fact, not fate. Years later, she would extend the argument in the book-length essay "AIDS and Its Metaphors."

An early and passionate opponent of the Vietnam War, Sontag was both admired and reviled for her political convictions. In a 1967 Partisan Review symposium, she wrote that "America was founded on a genocide, on the unquestioned assumption of the right of white Europeans to exterminate a resident, technologically backward, colored population in order to take over the continent."

In her rage and gloom and growing despair, she concluded that "the truth is that Mozart, Pascal, Boolean algebra, Shakespeare, parliamentary government, baroque churches, Newton, the emancipation of women, Kant, Marx, Balanchine ballets, et al., don't redeem what this particular civilization has wrought upon the world. The white race is the cancer of human history; it is the white race and it alone — its ideologies and inventions — which eradicates autonomous civilizations wherever it spreads, which has upset the ecological balance of the planet, which now threatens the very existence of life itself."

Considering herself neither a journalist nor an activist, Sontag felt an obligation as "a citizen of the American empire" to accept an invitation to visit Hanoi at the height of the American bombing campaign in May 1968. A two-week visit resulted in a fervent essay seeking to understand Vietnamese resistance to American power.

Critics excoriated her for what they regarded as a naive sentimentalization of Vietnamese communism. Author Paul Hollander, for one, called Sontag a "political pilgrim," bent on denigrating Western liberal pluralism in favor of venerating foreign revolutions.

That same year, Sontag also visited Cuba, after which she wrote an essay for Ramparts magazine calling for a sympathetic understanding of the Cuban Revolution. Two years later, however, she joined Peruvian novelist Mario Vargas Llosa and other writers in publicly protesting the regime's harsh treatment of Heberto Padilla, one of the country's leading poets. She also denounced dictator Fidel Castro's punitive policies toward homosexuals.

Ever the iconoclast, Sontag had a knack for annoying both the right and the left. In 1982, in a meeting in Town Hall in New York to protest the suppression of Solidarity in Poland, she declared that communism was fascism with a human face. She was unsparing in her criticism of much of the left's refusal to take seriously the exiles and dissidents and murdered victims of Stalin's terror and the tyranny communism imposed wherever it had triumphed.

Ten years later, almost alone among American intellectuals, she would called for vigorous Western — and American — intervention in the Balkans to halt the siege of Sarajevo and to stop Serbian aggression in Bosnia and Kosovo. Her solidarity with the citizens of Sarajevo prompted her to make more than a dozen trips to the besieged city.

Then in the aftermath of the Sept. 11, 2001, terrorist attacks, Sontag offered a bold and singular perspective in the New Yorker. "Where is the acknowledgment that this was not a 'cowardly' attack on 'civilization' or 'liberty' or 'humanity' or 'the free world' but an attack on the world's self-proclaimed superpower, undertaken as a consequence of specific American alliances and actions?" She added, "In the matter of courage (a morally neutral virtue): Whatever may be said of the perpetrators of Tuesday's slaughter, they were not cowards."

She was pilloried by bloggers and pundits, who accused her of anti-Americanism.

Sontag had never been so public as she became over the next three years, publishing steadily, speaking constantly and receiving numerous international awards, including Israel's Jerusalem Prize, Spain's Prince of Asturias Award for the Arts, and Germany's Friedenspreis (Peace Prize). Upon accepting the prize from Jerusalem's mayor, Ehud Olmert, Sontag said of Israel's policies toward the Palestinians: "I believe the doctrine of collective responsibility as a rationale for collective punishments [is] never justified, militarily or ethically. And I mean of course the disproportionate use of firepower against civilians."

Last March, she was found to have a condition that, if left untreated, would be fatal: a pre-acute leukemia that doctors concluded was a consequence of the chemotherapy she had undertaken to rid herself of a uterine sarcoma discovered five years before. A little more than four months after the diagnosis, she received a partial bone marrow transplant.

In an interview for the Paris Review, in 1995, Sontag was asked what she thought was the purpose of literature.

"A novel worth reading," she replied, "is an education of the heart. It enlarges your sense of human possibility, of what human nature is, of what happens in the world. It's a creator of inwardness." She was the cartographer of her own literary explorations. Henry James once remarked, "Nothing is my last word on anything." For Sontag, as for James, there was always more to be said, more to be felt.

She is survived by her son, David, and a sister, Judith Cohen.

Her papers — manuscripts, diaries, journals and correspondence — as well as her 25,000-volume personal library were acquired by the UCLA Library in 2002 and will be housed in the Charles E. Young Research Library Department of Special Collections.

HARRISBURG — The State Supreme Court has rejected Attorney General Kathleen Kane's attempt to throw out a grand jury investigation into whether she or someone in her office leaked investigative secrets to a newspaper to discredit critics.

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